MOLECULAR DIAGNOSIS OF DUCHENNE/BECKER MUSCULAR DYSTROPHY: ANALYSIS OF EXONS DELETION AND CARRIER DETECTION

Objective: Duchenne and Becker Muscular Dystrophy (DMD and BMD) are X-linked conditionsresulting from a defect in the dystrophin gene located at Xp21.2. DMD is the mostfrequent neuromuscular disease in humans (1/3500 male newborns). In approximately65% of DMD and BMD patients, deletions in the dystrophin gene have been identified asthe molecular determinant. The frequency and distribution of dystrophin gene deletions inDMD/BMD patients from different populations are different.The aim of this study was to delineate various types of deleted exons and their frequencyin affected male patients and identification of carrier females by linkage analysis.Materials and Methods: In this study 100 unrelated patients with DMD/BMD were studiedfor intragenic deletions in 28 exons and the promoter region of the dystrophin geneusing multiplex PCR. We also performed linkage analysis within the dystrophin gene utilizing8 short tandem repeat markers.Results: Fifty-two (52%) patients showed intragenic deletions. A total of 81% of the deletionswere located at the distal hot spot region (44-55 exons) and 19% of the deletionswere located at the proximal region (exon 2-19). The most frequent deleted exons were47(16%), 48 and 46 (11%).Most of the STR markers showed heterozygosity in the families studied. The linkageanalysis was useful for detecting carrier status.Conclusion: The present study suggests that intragenic dystrophin gene deletions occurwith the same frequency in Iranian patients compared with other ethnic groups.